Old is Gold: Re-evaluating Therapies in OAB

Introduction and prevalence of overactive bladder (OAB)

The Standardisation Subcommittee of the International Continence Society (ICS) defines OAB as urgency, with or without urge incontinence, usually with frequency and nocturia.¹Wein AJ, Rovner ES. Definition and epidemiology of overactive bladder. Urology. 2002 Nov;60(5 Suppl 1):7-12.   OAB is a common condition in both men and women and significantly impacts the overall quality of life, sexual function, sleep and mental health. In spite of the similarity in prevalence of OAB between the two sexes, sex-specific differences of various symptoms within the OAB complex exist. Anatomical and physiological differences in the lower urinary tract of males and females may help to explain this variations.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

The prevalence of incontinence in women varies from 14% to 40.5% (23.5% using the ICS definition), while in men, it varies from 4.6% to 15%. In women, urge and mixed incontinence is seen in 51% of cases, whereas in men the combined total was 92%.³Tyagi S, Thomas CA, Hayashi Y, Chancellor MB. The overactive bladder: Epidemiology and morbidity. Urol Clin North Am. 2006 Nov;33(4):433-8.   Various studies report the prevalence of OAB.

EPIC study

The EPIC study is one of the largest population-based, crosssectional telephone survey of adults aged >18 years to study the prevalence of lower urinary tract symptoms (LUTS) and OAB. It was conducted in five countries, including Canada, Germany, Italy, 2 S weden and the UK.

The prevalence of LUTS suggestive of OAB was 10.8% in men and 12.8% in women. Although the incidence of LUTS was in general was similar, it was more common in women (66.6%) than men (62.5%). Among the participants aged 40-59 years, storage symptoms were experienced by 21% of men and 56% of women. The study reported higher rate of urinary continence in women than men (13.1% vs. 5.4%). Nocturia was 48.6% in men and 54.5% in women.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

NOBLE study

The National Overactive Bladder Evaluation (NOBLE) study focused on the impact of OAB on quality of life, sleep and general mental health. Overall the study reported no significant differences in the OAB prevalence between the two sexes (16% in men, 16.9% in women).

According to the study, certain symptoms after the age of 60 years are predominant in men.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

In both men and women, urge incontinence increases with age, ranging from 2-19% in women after 44 years of age and 0.3-0.9% in men with marked increase after 64 years. The study also discovered an association between OAB with UI and body mass index (BMI) in women. Women with BMI >30 were 2.2 times more likely to have OAB with UI than women with BMI <24.8.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

EpiLUTS study

The Epidemiology of Lower Urinary Tract Symptoms (EpiLUTS) survey was a population-based, cross-sectional survey conducted to evaluate the prevalence of OAB and to update the results of the NOBLE survey done in 2003. The prevalence of OAB depended on how OAB was defined. The overall prevalence was 35.6% when symptoms were defined as “sometimes”, while the prevalence decreased to 24.7% when defined as “often”.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

The EpiLUTS study reported sex-specific differences. The prevalence rates of OAB symptoms “sometimes” and “often” were 27.2% and 15.8%, respectively, in men, whereas in women, the prevalence rates of OAB symptoms “sometimes” and “often” were 43.1% and 32.6%, respectively. All four symptoms of OAB, urgency, urge incontinence, frequency, and nocturia, were found in 16% of men and 20% of women.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

Milsom study

To determine the prevalence and symptoms of OAB Milsom et al., conducted a population-based prevalence study. The Milsom study found an overall prevalence of OAB symptoms of 16.6%. Although the overall prevalence of frequency and urgency was comparable irrespective of sex, urge incontinence was found to be more prevalent among women than men.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

The prevalence of OAB symptoms in men increases slowly until the age of 70 years, with a sharp increase after 75 years of age, and a slight fall in prevalence between the ages of 70 years and 75 years. In women, there is also a steady increase seen until the age of 60 years, with a leveling off seen between 60 years and 70 years of age and a gradual increase in prevalence thereafter.²Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.

Pathophysiology

Though numerous clinical studies have been performed, the cause of OAB has still not been established. According to recent research on OAB, three main factors have been proposed for the cause of OAB: Myogenic, neurogenic and urotheliogenic.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Myogenic

The myogenic factor is the alterations in the properties of the detrusor myocytes that are a necessary condition for the production of an involuntary detrusor contraction. This in turn causes an unstable increase of intravesical pressure. Increase in intravesical pressure during voiding may result in periodic ischaemia of the bladder. This results in damage to some intrinsic neurons in the bladder wall and secondary changes in smooth muscle properties over time.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

The excitability and electrical coupling between cells is increased due to these changes. A local contraction occurring in any part of the detrusor will then spread throughout the bladder wall, resulting in coordinated myogenic contraction of the entire bladder. Also, partial denervation of the detrusor may cause supersensitivity of detrusor to neurotransmitters, which subsequen tlyaugments the response to stimulation.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Neurogenic factor

The neurogenic factor suggests that damage to central inhibitory pathways in the brain and spinal cord or sensitisation of peripheral afferent terminals in the bladder can unmask primitive voiding reflexes that trigger detrusor overactivity. This can result from damage to the brain, which can induce detrusor overactivity by suppressing suprapontine inhibition; damage to axonal pathways in the spinal cord leads to the emergence of primitive spinal bladder reflexes triggered by C-fibre bladder afferent neurons.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Neurogenic causes may be seen in patients who have multiple sclerosis, cerebrovascular events and Parkinson’s disease. Kessler et al., reported that thalamic deep brain stimulation resulted in an earlier desire to void and decreased bladder capacity, suggesting a regulatory role of the thalamus in lower urinary tract function.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Urotheliogenic factor

Urothelium, according to studies is not just a passive barrier, but is also a responsive structure that is capable of detecting thermal, mechanical and chemical stimuli. Transmitters released from the urothelium may alter the excitability of afferent nerves and affect detrusor muscle contractility. ⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Urothelium absence may cause an increase in the spontaneous activity of detrusor. According to a study by Shioyama et al., chronic urothelial injury leads to an increase in urinary frequency and a decrease in voiding volume. Thus, the urothelium is an important participant in the pathophysiology of OAB.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

BOO and OAB

In patients with lower urinary symptoms, bladder outlet obstruction (BOO) is diagnosed in 31-68% of patients with OAB. The preoperative frequency of OAB varies from 25% in patients without BOO to 62% in those with BOO.

Persistent OAB symptoms were reported in 25-31% of OAB patients who underwent transurethral resection of prostate. However, the rate of de novo OAB has been reported to be at most 10% in patients who have had a prostatectomy. BOO-induced OAB has been attributed to change in nerve growth factor (NGF), TREK1, K+ channel, muscarinic and purinergic receptors.⁴Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.

Management

Management strategies for OAB are described below.

Conservative management

For mild and easily manageable symptoms a conservative approach is reasonable.

Lifestyle interventions

In patients with lower urinary tract symptoms and voiding dysfunction, the frequency-volume chart, or urinary diary, is an important investigation tool that facilitates history taking regarding frequency, nocturia and volume voided. It has shown to be valuable and reliable for the assessment of micturition patterns. Moderate intake of 1-1.5 litres of fluid per day reduces urine production and can ease symptoms. Drug regimens avoiding diuretics, control of chronic cough and constipation, cessation of smoking, exclusion or treatment of urinary tract infection, and weight reduction are desirable. In the elderly, alcohol, caffeine, and medication such as diuretics are major causes of acute incontinence.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Physiotherapy

Jeffcoate and Francis, in the 1960s first advocated the practice of voiding “by the clock” for urge incontinence. Although behavioural modification improves central control of bladder function, it requires high levels of motivation and encouragement, and suffers from high relapse rates. But this type of treatment avoids the mortality and morbidity of surgery, and the side-effects of drug treatment.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

In a review of the randomised clinical trials of conservative treatments, Berghams et al., reported strong evidence that bladder drill is more effective than no treatment, and weak evidence that bladder drill is better than drug treatment. Due to inadequate clinical trials, there is insufficient evidence of the efficacy of bladder drill with drug treatment, bladder drill with pelvic floor exercises and biofeedback, or biofeedback and beha vioural therapy.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Pharmacologic therapy

The pharmacological interventions for the treatment of OAB should take into account patient perceived outcomes, rather than simple symptom resolution alone.⁶Sweeney P, Mutambirwa S, Van An N, et al. Flavoxate in the symptomatic treatment of overactive bladder: a meta-analysis. Eur Rev Med Pharmacol Sci. 2016 Sep;20(17):3703-12.   Pharmacotherapy for OAB is based on inhibiting the action of acetylcholine, which stimulates detrusor contraction via muscarinic (M) receptors.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Anticholinergics

Anticholinergic drugs are the basis of pharmacotherapy. The 7drugs used for the treatment of OAB are described below

Oxybutynin

Oxybutynin has highest affinity to M1 and M3 receptor and most studies have shown that it reduces incontinence episodes by 55-83%. Adverse effects such as dry mouth, constipation and blurred vision are dose dependent and lead to discontinuation in up to 25% of patients. Extended release (ER) preparations have fewer adverse effects but are of similar efficacy to immediate release (IR) preparations. The transdermal route is comparable to IR preparations with a better adverse effect profile. The main adverse effect is pruritus at the site, which has been reported in 14% of patients.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Tolterodine

Tolterodine appears to target bladder over salivary gland receptors. According to a pooled analysis of four studies between 1996 and 1998, there were reductions in micturition frequency of tolterodine 2 mg twice-daily (2.3), oxybutynin 5 mg thrice-daily (2.0) and placebo (1.4) per 24 hrs. Reduced episodes of urge urinary incontinence were reported.

Compared to tolterodine (40%), adverse effects, particularly dry mouth, were more common with oxybutynin (78%). Although tolterodine was deemed more efficacious, the clinical differences in outcome measures may not be that significant.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Trospium chloride

This is an atropine derivative with predominantly antimuscarinic effects and has a low incidence of central nervous system (CNS) adverse effects because of its low solubility across the blood-brain barrier. One randomised controlled trial showed superiority of trospium chloride in improving the urodynamic parameters by 30% compared to placebo.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Propiverine

Propiverine has combined anticholinergic and calcium channel blocking actions and is the most commonly used drug for OAB in German y, Austria and Japan.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Solifenacin

Solifenacin is a recent, once-daily antimuscarinic drug which has been shown to improve all the major symptoms of OAB.⁷Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.

Darifenacin

Darifenacin, a tertiary amine with moderate lipophilicity and a highly selective M3 receptor antagonist, has been found to have a 5-fold higher affinity for the human M3 receptor relative to the M1 receptor. Darifenacin is equipotent with atropine in the ileum and bladder and six times less potent at inhibiting muscarinic receptors in the salivary gland.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Botulinum toxin

Out of the seven immunologically distinct antigenic subtypes of botulinum toxin, type A is the most widely used. Botulinum toxin A (Botox) is a purified neurotoxin complex, which blocks the release of acetylcholine and other transmitters from presynaptic nerve endings that results in decreased muscle contractility and muscle atrophy at the injection site. Botox cannot cross the blood-brain barrier and hence has no CNS side effects.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

β3 agonist

β3 adrenoceptors activation relaxes the detrusor muscle. This lead to the development of first β3 adrenoceptor agonist. The first drug in this class, approved for the treatment of OAB symptoms is mirabegron. It is licensed in Japan, USA, Europe and Canada.

Mirabegron has been comprehensively studied in phase II and III trials and has significant improvement in key overactive bladder parameters compared to placebo. The incidence of side effect like dry mouth is less compared to anticholinergics. It can be used safely in combination with solifenacin and tamsulosin. The drug however is presently not available in India.⁸Warren K, Burden H, Paul Abrams. Mirabegron in overactive bladder patients: efficacy review and update on drug safety. Ther Adv Drug Saf. 2016 Oct; 7(5):204-216.

Antispasmodic drugs

Antispasmodic drugs are indicated for OAB as they relieve symptoms of OAB, have proven to be effective in suppressing premature detrusor contractions and enhance bladder storage. Flavoxate is a selective uro-specific antispasmodic that acts only on smooth muscles of urinary bladder (detrusor muscle). ⁹Hesch K. Agents for treatment of overactive bladder: a therapeutic class review. Proc Bayl Univ Med Cent. 2007 Jul;20(3):307-314.

Flavoxate has no antimuscarinic activity, and is mainly devoid of antimuscarinic/anticholinergic side effects seen with other drugs. It has a favourable tolerability profile to suggest its wide applicability in subpopulations of patients with OAB and urinary incontinence. ⁹Hesch K. Agents for treatment of overactive bladder: a therapeutic class review. Proc Bayl Univ Med Cent. 2007 Jul;20(3):307-314.

Fla voxate has advantages over anticholinergics :¹⁰Data on file.

• Increases bladder capacity
• Reduces post-void bladder volume
• No risk of urine retention
• Preferred by the patient

Flavoxate

Among various pharmacological interventions for the treatment of OAB, flavoxate has been the drug of choice among the urologists and the general physicians for decades globally. Although flavoxate is a globally accepted molecule, a metaanalysis of the available publications for efficacy, safety and tolerability of flavoxate has not been conducted. The following study evaluates the strength of evidence of clinical effectiveness of safety and tolerability of flavoxate in the symptomatic treatment of OAB.⁶Sweeney P, Mutambirwa S, Van An N, et al. Flavoxate in the symptomatic treatment of overactive bladder: a meta-analysis. Eur Rev Med Pharmacol Sci. 2016 Sep;20(17):3703-12.

Aim

A meta-analysis on flavoxate was conducted to investigate based on available evidence, its efficacy, side effects profile, and effects on frequency, urinary incontinence, mixed incontinence, nocturia, unpleasant urination and stranguria (defined as slow and painful urination or burning).⁶Sweeney P, Mutambirwa S, Van An N, et al. Flavoxate in the symptomatic treatment of overactive bladder: a meta-analysis. Eur Rev Med Pharmacol Sci. 2016 Sep;20(17):3703-12.

Methods

• Review articles, original studies and case reports on MEDLINE, the Cochrane Library, Google Scholar, Scirus, internal repository, etc. were searched using the keyword “flavoxate”.
• For the primary outcome, the comparative data of flavoxate vs. comparator was extracted for following parameters- overall efficacy and its side effect profile.
• Similarly, as for secondary outcome, data were extracted for flavoxate per se for overall efficacy, frequency, urinary incontinence, mixed incontinence, nocturia, unpleasant urination, stranguria and its side effect profile and were analysed using Comprehensive Meta-Analysis (CMA) software version 2.0.

Results

The databases searches yielded 86 publications and according to the inclusion and exclusion criteria, 43 relevant studies were identified.

Primary efficacy analysis

• Flavoxate vs. Placebo: Out of the 8 studies (n = 262) 3 studies showed a reduction in the risk with flavoxate as compared with placebo.
• Flavoxate vs. Oxybutynin: All the three studies that included oxybutynin (n = 101, in both the flavoxate and oxybutynin group) showed a similar efficacy of flavoxate and oxybutynin.
• Flavoxate vs. Others: In two studies, flavoxate showed higher efficacy compared to emepronium. Overall flavoxate was more effective than propantheline.

Primary safety analysis

• Flavoxate vs. Placebo: The incidence of adverse events was comparable in the placebo and flavoxate groups in all the five studies.
• Flavoxate vs. Emepronium: One study showed that flavoxate is associated with significantly (p < 0.05) fewer side effects as compared with emepronium.
• Flavoxate vs. Propantheline: Three papers reported lower incidence of adverse effects with flavoxate compared to propantheline.
• Flavoxate vs. Others: One study reported significantly lower side effect in flavoxate (26.8%) compared to oxybutynin (90.2%).

Secondary analysis

• Out of the 35 studies included in the efficacy analysis of flavoxate per se (n = 2,005), 19 showed significant results (p < 0.05).
• The analysis of flavoxate on frequency (24 studies involving 989 patients) showed decrease in frequency in all individual studies, reaching statistical significance in 11 individual studies (p < 0.05).
• The effect of flavoxate on urinary incontinence as derived from 21 reports involving 2,104 patients was evident in all cases, reaching statistical significance in 10 studies (p < 0.05).
• The effect of flavoxate on nocturia was investigated in 9 researches (n = 1,186), out of which nocturia was decreased in all studies, but was significantly decreased in three (p < 0.05).

.

The meta-analysis reported that flavoxate was effective and welltolerated, with almost negligible side effects. Thus, flavoxate is worthy of consideration for the treatment of OAB.

Electrical therapy

Electrical stimulation of peripheral nerves can be used to cause muscle contraction, to activate reflexes, and to modulate some functions of the central nervous system. Electrical stimulation can be used as medical treatment for incontinence and urinary retention, as it produces bladder or sphincter contraction and micturition if applied to the nerves controlling the lower urinary tract. ¹¹Jezernik S, Craggs M, Grill WM, et al. Electrical stimulation for the treatment of bladder dysfunction: current status and future possibilities. Neurol Res. 2002 Jul;24(5):413-30.

Sacral neuromodulation

Stimulation of the S3 nerve root by an implanted electrical pulse generator can provide effective relief from frequency urgency symptoms. The stimulator, a small electrical pulse generator, is approximately the same size as a cardiac pacemaker. It is commonly implanted in the upper outer quadrant of the buttock.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

A prospective randomised trial of sacral neuromodulation vs. delay, incontinence episode frequency (IEF), reported a reduction in IEF of more than 50% at 6 months. However, neuromodulation is very expensive and patients need expert assessment and management. Although it is not suitable for routine use, sacral neuromodulation appears to be useful for a selected minority. Most common complications reported are generator site pain (15.9%) and implant site pain (19.1%). Lead migration may occur in up to 7%.

The surgical revision of technical failures and complications was 32.5%. Due to progress of technological development of generators and implant leads, complications and failures may be expected to reduce in the future.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Percutaneous tibial nerve stimulation (PTNS)

PTNS is a less invasive treatment alternative to sacral neuromodulation, since surgical implantation is not required. Studies haves been performed on stimulation of the tibial nerve, which originates from the L4-S3 lumbosacral plexus as part of the sciatic nerve, for treatment of OAB. PTNS is typically performed via a needle electrode inserted above the ankle and stimulation is delivered for 30 minutes once a week for 12 weeks. Randomised controlled studies report significant improvement with OAB symptoms.¹²McGee MJ, Amundsen CL, Grill WM. Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury. J Spinal Cord Med. 2015 Mar;38(2):135-46.

Pudendal nerve stimulation (PNS)

PNS is electrical stimulation of the pudendal nerve, containing both sensory and motor fibres, or electrical stimulation applied to distal branches (dorsal genital nerve). The pudendal nerve, a somatic nerve in the pelvic region, originates from the sacral spinal cord at levels S2-S4 in humans. Pudendal nerve can be accessed for electrical stimulation via a transgluteal incision or less-invasive percutaneous or transcutaneous approaches. In patients who do not respond well to sacral neuromodulation, PNS may be an alternative neuromodulation therapy for the treatment of refractory OAB.¹²McGee MJ, Amundsen CL, Grill WM. Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury. J Spinal Cord Med. 2015 Mar;38(2):135-46.

Other surgical interventions

Other surgical solutions for OAB include detrusor myectomy, augmentation cystoplasty, or urinary diversion.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Clam augmentation cystoplasty

Augmentation cystoplasty is used to increase the size of the urinary reservoir and make the bladder less contractile. Commonly indicated in patients who lack enough bladder capacity or detrusor compliance; who manifest devastating frequency urgency symptoms, with urge incontinence, urinary tract infections; who have failed to derive benefit from medical treatment; whose lifestyle is severely limited; or with high pressure urine storage endangering the upper renal tracts.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

This procedure involves almost complete bisection of bladder. A patch of gut (usually ileum) equal in length to the circumference of the bisected bladder (about 25 cm) is sewn in place.

The procedure often cures the symptoms of detrusor overactivity. But the procedure may result in inefficient voiding, and patients have to learn to strain to void or sometimes permanently have to resort to clean intermittent self-catheterisation.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Detrusor myectomy

In detrusor myectomy, a large bladder diverticulum with no intrinsic contractility is created by excising the whole thickness of the detrusor muscle from the dome of the bladder. It provides an alternative to clam cystoplasty by increasing functional bladder capacity without the complications of bowel interposition. While episodes of incontinence are reduced, there is little improvement 5in functional capacity and thus frequency remains problematic.

Urinary diversion

Urinary diversion is used as a last resort for women with severe detrusor overactivity or neurogenic detrusor overactivity who cannot manage clean intermittent catheterisation. In the procedure, an abdominal stoma for urinary diversion is created by utilising an ileal conduit. An alternative is to form a continent diversion using the appendix or ileum which may then be drained using self-catheterisation.⁵Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.

Conclusion

OAB is a common and distressing condition that impacts the quality of life significantly. Compared to that reported for the general population the prevalence of OAB in the male urologic veterans is almost 5-fold higher. Pharmacological treatment, in addition to bladder retraining, remains important in the management of women with symptoms of the OAB syndrome. There is convincing evidence that anticholinergic agents are effective for the treatment for OAB.

Flavoxate, out of the many pharmacological interventions, is the drug of choice among the urologists and has shown its superiority in treating symptoms of OAB over emepronium, oxybutynin, propantheline. Apart from pharmacological therapy, electrical therapy and surgery are other options for the management of OAB.

References

1. Wein AJ, Rovner ES. Definition and epidemiology of overactive bladder. Urology. 2002 Nov;60(5 Suppl 1):7-12.
2. Eapen RS and Radomski SB. Review of the epidemiology of overactive bladder. Res Rep Urol. 2016; 8: 71-76.
3. Tyagi S, Thomas CA, Hayashi Y, Chancellor MB. The overactive bladder: Epidemiology and morbidity. Urol Clin North Am. 2006 Nov;33(4):433-8.
4. Meng E, Lin Wei-yu, Lee Wei-Chia, Chuang Yao-Chi. Pathophysiology of Overactive Bladder. 2012;4(1):48-55.
5. Srikrishna S, Robinson D, Cardozo L, and Vella M. Management of overactive bladder syndrome. Postgrad Med J. 2007 Jul; 83(981): 481-486.
6. Sweeney P, Mutambirwa S, Van An N, et al. Flavoxate in the symptomatic treatment of overactive bladder: a meta-analysis. Eur Rev Med Pharmacol Sci. 2016 Sep;20(17):3703-12.
7. Munjuluri N, Wong W. Anticholinergic drugs for overactive bladder: a review of the literature and practical guide. The Obstetrician & Gynaecologist. 2007;9:9-14.
8. Warren K, Burden H, Paul Abrams. Mirabegron in overactive bladder patients: efficacy review and update on drug safety. Ther Adv Drug Saf. 2016 Oct; 7(5):204-216.
9. Hesch K. Agents for treatment of overactive bladder: a therapeutic class review. Proc Bayl Univ Med Cent. 2007 Jul;20(3):307-314.
10. Data on file.
11. Jezernik S, Craggs M, Grill WM, et al. Electrical stimulation for the treatment of bladder dysfunction: current status and future possibilities. Neurol Res. 2002 Jul;24(5):413-30.
12. McGee MJ, Amundsen CL, Grill WM. Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury. J Spinal Cord Med. 2015 Mar;38(2):135-46.